https://www.pbainbridge.co.uk/2018/12/email-on-form-submit.html

Email on Form submit.gs

function onFormSubmit(e) {
  
  // get spreadsheet info
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var dataSheet = ss.getSheetByName('Form responses 4');
  
  // get Form data
  var formValues = e.namedValues; // allows row Headers to be specified when looking-up values
  var theRow = e.range.getRow(); // this is the row the Form data is written to
  var name = formValues['Name'];
  var username = formValues['Username'];
  var bookTitle = formValues['TItle of the returned book'];
  var receipt = formValues['Receipt'];
  
  
  // ************ START OF EDIT EMAIL SECTION ************
  // edit text within single quotes below to change email subject
  var subject = 'Automatic message from the Refund form';
  
  // edit text within single quotes below to change email body
  var body = 'This is an automatic message generated by the Refund form.' + " \n\n";
  body+= 'Information provided\n------------------------------------------- \n';
  body+= 'The persons name is: ' + name + " \n";
  body+= 'The persons course is: ' + username + " \n";
  body+= 'Title of the returned book: ' + bookTitle + " \n";
  body+= 'Link to receipt: ' + receipt + " \n";
  Logger.log(body);
  
  // edit any options for email below
  var options = {noReply:true};
  
  // send email
  MailApp.sendEmail('mail@example.com', subject, body, options); 
  // ************ END OF EDIT EMAIL SECTION **************
  
  
  // writes 'Email sent' into alert column
  var alertCell = dataSheet.getRange(theRow, 7);
  alertCell.setValue('Email sent');
  
}